Synchronizing Methods and Blocks In Java
In the Java programming language, synchronization methods in multithreaded tasks are used to control or manage full access to shared resources within a program. When Java users are executing or running multiple thread tasks simultaneously in real time within a single program.
Without synchronization methods in Java thread tasks, two or more program task threads could access and modify the same data at the same time, resulting in different or false results being displayed. This condition or problem in Java is known as a race condition.
To achieve thread task synchronization in Java, Java provides its users with the synchronized keyword.
Why do we need synchronization methods in a Java program?
Let’s assume that a user has two thread tasks accessing the same bank account data.
class User_Account {
int Final_balance = 8789;
void withdrawals(int total_amount) {
Final_balance = Final_balance – total_amount;
}
}
Here, in this condition, two thread tasks apply or attempt to withdraw money from a user account at the same time. In such a condition, both thread tasks may display the old deposit amount balance information from the same user account before any system updates are completed.
In such a condition, a false result may be displayed multiple times.
In such a condition, the synchronization method ensures that in the current system, only one thread task can execute a critical section for the same lock at a time.
Synchronized Method in Java.
In the Java programming language, the synchronized method is a user-defined, custom-declared method that is invoked by declaring the synchronized keyword in a thread program.
Synchronized Method Syntax.
synchronized void methodName() {
// Here we create a user-defined critical section.
}
Example of a synchronized method.
class Tester {
private int count_Value = 0;
synchronized void increase() {
count_Value++;
}
int getcount_Value() {
return count_Value;
}
}
Here, in this example, if multiple threads call the task increase() function method on the same Tester object, the synchronization method blocks them from entering that synchronized method simultaneously.
How a synchronized method works in a thread.
Tester t = new Tester();
Here, for a single instance of the synchronized method.
synchronized void increase()
Here, the lock is connected to the object t.
Conceptually, the method concept.
Thread Task 1 → Thread 1 acquires the object lock → executes the increase() function
|
v
Finally releases the object lock
Thread Task 2 → Thread 2 acquires the object lock → executes the increase() function
In such a situation, a user-defined program thread (the first task) must wait on this process, while the second thread task holds the monitor lock value of the same object.
Synchronized Block Concept in Java.
Sometimes we don’t want to synchronize the entire method.
Instead, we may want to synchronize only a specific part of the method. In such a case, we use a synchronized block.
Synchronized Block method syntax.
synchronized(object) {
//Here we create a user-defined thread task critical section.
}
Example of a Synchronized Block method.
class Tester {
private int count_value = 0;
void increase() {
synchronized(this) {
count_value++;
}
}
int getcount_value() {
return count_value;
}
}
Here, in this example, only.
count_value++;
This is a synchronized method.
Furthermore, the increase() function method does not require a lock.
Explanation of Synchronized Method vs Synchronized Block.
| # | Synchronized java method | Synchronized java block |
| 1. | We can use synchronized method with a complete java program method | We can use it with specific synchronized with a particular block portion or area |
| 2. | It used to lock the entire java program thread method | It locks only a specific section or portion on java thread |
| 3. | Synchronized java method is simple to write for user | Synchronized java block provides more control then other |
| 4. | Synchronized java method may lock more code than its system necessary | Synchronized java block can reduce unnecessary thread method or block it from locking |
| 5. | Synchronized java method uses the method’s associated with only its secure lock | Synchronized java block you explicitly specify the lock object or portion |
Example of a synchronized method in a Java thread task.
Here, Java users can analyse a complete online ticket booking system in detail.
class TicketBookingSystem {
private int ticket = 1;
synchronized void buyTicket() {
if (book_tickets > 0) {
System.out.println(“Ticket received by “
+ Thread.currentThread().getName());
book_tickets–;
} else {
System.out.println(“No ticket ready to buy”);
}
}
}
In this example, two thread tasks may be trying to book the same ticket.
public class Main {
public static void main(String[] args) {
TicketBookingSystem tic_booking = new TicketBookingSystem();
Thread th1 = new Thread(() -> tic_booking.bookTicket(), “Buyer First”);
Thread th2 = new Thread(() -> tic_booking.bookTicket(), “Buyer Second”);
th1.start();
th2.start();
}
}
Because buyTicket() in this example is a synchronized thread task or method, only one thread can execute it at a time for that booking object.
Example of a synchronized block in a Java thread task.
Let’s assume we have some code in a user-defined program thread task method that doesn’t require synchronization.
class Tester {
private int count_value = 0;
void increase() {
System.out.println(“Preparing to increase tester…”);
synchronized (this) {
count_value++;
}
System.out.println(“Tester increment completed.”);
}
}
Critical sections only.
synchronized (this) {
count_value++;
}
This is a secure synchronized thread task method.
This method is used when the user-defined synchronized thread task method contains a lot of user-defined custom code, but only a small portion of it can access shared data when needed.
Lock an object in a Java synchronized thread task block.
Java users can use a separate object as a thread task object lock.
class Sample {
private final Object lock = new Object();
void preview() {
synchronized (lock) {
System.out.println(“Critical thread section defined”);
}
}
}
In this example, the thread object lock is used as a monitor object.
This method can be used in Java when Java users want to control or manage synchronization in a clear order.
Static synchronized method concept in Java threads.
A static task method in a Java program can also be synchronized if needed.
class Sample {
static synchronized void preview() {
System.out.println(“User defined static synchronized method defined”);
}
}
The main difference between this method is that a static synchronized method in an existing program locks the class object, not a single object instance.
For example.
Sample.class
Here, the Sample class method acts as a lock.
Key points about synchronizing methods and blocks.
The synchronized method in a Java thread provides the Java user with a mutual exclusion concept.
This concept ensures that only one thread task can run code protected by the same lock at a time.
Java synchronization is thread task object-specific.
Synchronization is thread task instance.
synchronized void preview()
Here, it locks the current thread object (this) function method.
In which two different thread task objects have separate locks defined.
Sample s1 = new Sample();
Sample s2 = new Sample();
In this example, the thread task method using the lock on s1 does not automatically block the thread using the lock on s2.
Java thread task synchronization also provides memory visibility.
In this example, any modifications made by a thread before releasing the monitor lock are displayed to other threads when they successfully acquire the same lock on the task or process.
Simple difference between the two methods.
Synchronized Java method.
synchronized void preview() {
// In this, a complete user-defined method is kept safe.
}
Synchronized Java block method.
void preview() {
// Normal Java thread program source code
synchronized(this) {
// This is only protected as of this section
}
// Normal Java program source code
}
Conclusion of Synchronizing Methods and Blocks with Java.
Synchronization in the Java programming language is a mechanism or user-defined thread task method used to control or manage access to resources shared by multiple threads in a Java task. It avoids race conditions in thread tasks and ensures that only one thread can execute a synchronized section secured by the same lock at a given task time. Java programs provide synchronization methods using the synchronized keyword. Synchronization for a Java program thread task can be implemented using a synchronized method or synchronized block. A synchronized method in a Java program locks the object associated with it for the execution of that method. Whereas, a user-defined program synchronized block allows synchronization of only a specific portion of the program code and provides greater control over the lock.
Synchronizing Methods and Blocks in Brief.
- Synchronized Java Method → Locks the entire thread method in a Java program.
- Synchronized Java Block → Locks only an essential section in a Java program.
- Purpose of both synchronized Java methods and blocks → Secures the program against thread safety and race conditions in Java programs.
